Nucleus alkylated phloracylophenones and procedure for the production of such compounds



United States Patent- O NUCLEUS ALKYLATED PHLORACYLOPHENONES s,AND;PROCEDURE- FOR-IHE ,PRODUGTION 20F 'SUCHf COMPOUNDS Wblfgang' RidlfMunich}'Gerrnany,=-assignor to Schwarz Laboratories, Inc., a corporation of=New York .NolDrawing. Application January 27, 1955 Serial 'No.'484,'585

4 Claims priority,"application-GermanyMarch'1, 1954 '11- Claims. (Cl.\260-.-586)' German Patent No. 899,198. teaches that in2,4,6- trihydroxyacylophenones (designated below as,type; A),

r-alkyL residues can, be "introduced .to form nucleus-alkyl- =atedderivativ,es thereof;by-exchangingthe monovalent poly.-substituted metal compounds of .2;4;6-.trihydroxy- :acylophenones with alkyl, alkenyl or aralkyl halides whose halogen is particularly reactive'(for.-examp1e,1-dimcthyl-allylbromide). In this procedure one operates in a solvent'(ben'zol, ether or ether plus some methanol) that .has: but slight activating effect upon the reactants, 'thus to lobtain compounds designated below as B, C --and D.

on on n con R2 00121 no on HO OH on on R: R, R2 00R .no, OH 0: OH

R: -R -R,,

, :It hasbeen ifourid, surprisingly, .that..these:nuclear- Y substitution reactants are.;:greatly facilitatedby'the ;:sel-lection I of; asparticulars ,classaof i solvents, more. especially solyents"which.haveaconsiderirble activating eliect'upon the reactants and are characterizedxby;acihightldielectric constant of the order of 10 or more and, preferably more 25 previously disclosed procedure.

Ce Patented Aug. 4, 1959 (3) Theyields of pure'nucleus' substituted'phloracylophenones of types'B 'toFare'about70percent'of theory. 'Also with the tri-v,wdimethyl allyl-alkaylation' described "in the'earlier patent,the compounds of type Dcafbe 5 "obtained according to"the1presentinvention 'with"'sub "stantially higher yields.

"(4) According to 'the" present invention,solvents'with considerable activating effect. upon the reactants, and "of high dielectric constantare usedto advantage, more particularlyithe-lower alkanols,"the.lower k'etones, distilled water and mixtures of these, and they, promote\ the krypto-ionic course of reaction between alkylhalidesand 'phloracylophenone-metal compound.

As noted, it is not necessary, according .to the-present l5 invention, that the halogen'be particularly reactive-min the saturated or unsaturated and. eventually: substituted alkyl, alkenylor aralkyl primary or secondary halidesmaybe used, thus permitting a much wider range of endeprod- ..ucts. Preferablyrthe alkyl halides are saturatedandhave 0 lesslthan carbon atoms in the chain. This new" feature irisnespecially valuable as .it permits thedirecbpreparation of nucleus substituted phloracylophenones Whicharefully saturated in all substituents andtherefore much. more stable than those products which-can be formed-.by my In the phloracylophenones used (typetA) orin their already-partially nucleus-substituted derivatives (of types B, C, Dand. F) Which:admit of further" nuclearsubstitution, thefurther t residue or residues can be selected as desired.

This new method of synthesis makes possible, :for-the first time, preparation of a Whole new series ofi-co'mpounds having antibiotic properties similar to those "reported for thennaturally occurring hop resin,.nlupulon, but-with the important practical advantage that-synthetic compounds can be made which are both :more stable and more potentv against specific groups 2 of organisms by appropriateselection of .the acyl; group, and thezialkyl, ialkenyl -or-aralkyl substituents attached to the'snucleus .at .the 3 and/or. 5. carbon position.

40 The further conditions-of the reaction such as concentrationof the: reactants the typeof :metal: compound ,and. the temperature of the. reactionare so ;choscnz.:that swift. exchange occurs while substantially avbidingzhydrolysis-ofathe starting materials, splitting-;of;2-thecacyl- .residues orsdecomposition of theproducts: of the process.

Thee-products of'the" process are worked 11p byousual ,procdure, such as extraction with alkalis, :rsublimat-ion, :chromatographyor. utilization of specific :solubility, 1 etc.

Products -Of-:th6= process possess xbacteriostatic iactivity 5o swhichainhibits growth of -a number"ofi-organismsiknown to .produce- .disease :or food spoilage,.:and lmayiialso be eased-tor th6:iPr0ducti0n of r'physiologically1active material.

. The general :-.=me'thod tis-i carried cent :in the 1 following manner. :Any suitable phloracylophenone or "partially 'nuclearly+substituted phloracylophenone .is. reacted -'in =a -liquid thathasconsiderable activating etfecttuponr the rer-tactants andzhas a high dielectric constant, and comprises :a; solution of methanol andvzalkali metal (onalkalimetrl :methylate suchiasnsodiumwmethylate)zto:which is added the halide of an-zalkyl, alkenyl or rara'lkyl-compound. -After thereactionv is complete, the excess methanol arid halidecoinpoundr:mayzb'e rdistilleduotf 'in 'vacuo; and the residue gitpartitioned vbetween suitable .:dilute aqueous alkaline .-solutions and an appropriate solvent 'suchflis ether'or petroleum-ether. The aqueous 'fractions are acidified to precipitate crude products, which are further fractionatedaccording to solubility andcrystallized finally from aqueouszm'ethanol or other suitable-solvents. The

-less-water-soluble substitution products can 'berecovered .from the anonFaqueous' layer in' the partitioning proce'ss. By varying-thematic of: the threecomponents: 1 phloracylophenone, alkali metal methylate, and halide compound, the production of either mono, di, di-geminal, tri, or tetra substituted nuclei can be favored. The method also permits preparation of substituted phloracylophenones with more than one kind of substituent, and it is possible to form a monodi, or tri substituted compound of one substituent and subsequently treat successively with one or more different halide compounds, thus adding a second, third or fourth type of alkyl, aralkyl, or aryl substituent to the nucleus, depending on the number of positions that are free.

EXAMPLE 1 Methyl substituted phlor-acetophenones (a) For monomethylation 4.0 g. of anhydrous phloracetophenone may be dissolved in 30 ml. of absolute methanol, added to a freshly prepared ice-cold solution of 0.547 g. sodium (1 equivalent) in 10 ml. of methanol, and then 20 g. of methyliodide (6 equivalents) are added. This is left standing for several hours in the refrigerator, then for 5 days at room temperature and worked up in the following manner.

The practically neutral reaction mixture is slightly acidified and the excess methanol and methyliodide distilled off in vacuo. The residue is taken up in ether, and the ether solution is then extracted successively with aqueous saturated sodium bicarbonate, 10 percent aqueous sodium carbonate, and, finally, with 2 N sodium hydroxide.

The sodium carbonate extract is washed with ether and then acidified, whereupon crude 3-methyl phloracetophenone precipitates as yellowish needles (2.77 grams equal to 64 percent of theory, M.P. 160-180 C.). After two recrysallizations from about 50 ml. of water, one obtains almost colorless clusters of needles M.P. 207 C. of the product identified in the title of Example 1. If the molar relationship of phloracetophenonezsodium methylatezmethyliodide is altered to 1:2:1 or 1:321 corresponding yields result of 3-methylphloracetophenone of 42 percent and 44 percent of theory, respectively. The essential point of control is that no more than one equivalent of alkali metal or of halide should be present if mono-substitution of the nucleus is to be favored. In view of the lower yield of the desired product here obtained, it follows that in general it is preferable to control monosubstitution by limiting the amount of alkali metal methylate to the equivalent number of nucleus substitutes required and providing some excess of halogen compound.

(b) For dimethylation, trimethylation, and tetra-methylation, the ratio of these reactants are respectively in the order of 1:2:6, 1:3:6, and 124:8. Here again the amount of excess halide used is somewhat less critical than the molar ratio of phloracylophenone to alkali metal methylate. In polymethylations, lesser proportions of lower homologues are generally formed which can be recovered from the reaction products as by-products, or recycled in the process.

As an example of polymethylation, 20 g. phloracetophenone is dissolved in 150 ml. of methanol, to which is added, while cooling, a solution of 8.21 g. (3 equiv.) sodium in 50 ml. methanol. Under further cooling 101.5 g. methyliodide (6 equiv.) is added and the red-brown solution is left standing for days at room temperature under exclusion of humidity and air. Then excess methyliodide and methanol are distilled off in vacuo and the residue is mixed with 250 ml. each of water and ether. After acidifying with dilute sulfuric acid to the pH of Congo red, the aqueous solution is shaken twice with 50 cc. ether, and the combined red colored ether extracts extracted 8 times with 30 cc. saturated aqueous potassium bicarbonate solution (followed with 10 percent soda solution and caustic as in Example 1 a).

Upon acidifying the bicarbonate solution, previously washed once with ether, a red-brown precipitate is formed of 14.08 g. (55.2 percent of theory), long spears and .prisms with.M.P. 140-l50 C. This amount is digested in the cold with 4 washings each of 50 cc. benzol. The residue not dissolved with cold benzol is recrystallized from 110 cc., 30 percent methanol and yields 10.20 g. (:40.8 percent of theory) 1-acetyl-3,3,S-trimethylcyclo- 5 hexa-1,5-diene-2,6-diol-4-one with M.P. 160. Upon dilution of the mother liquor of the latter compound with about 100 cc. of water 1-acetyl-3,3-di-methyl-cyclohexa- 1,5-diene-2,6-diol-4-one crystallizes out 1.0 g. '4.3 percent of theory) M.P. 169 C. The combined filtered cold 10 benzol extracts are concentrated, and the residue recrystallized from 30 percent methanol: 0.28 g. (=l.l percent of theory) 1-acetyl-3,3,5,5-tetra-methyl-cyclohexa-1-ene-2-ol-4,6 dione with M.P. 54. The 3,3- and the 3,5-dimethyl compounds can be isolated from the soda extract by acidification and recrystallization from 30 percent methanol, yielding conjointly about 3 percent to 5 percent of needles with M.P. 174 to 176 and M.P. 220 C. respectively. The mixture of the 3,3 and 3,5 dimethyl compound may be separated, if desired, by fractionation according to solubility and crystallization If one works in concentrated or less concentrated methanolic solution with such trimethylation formulations and uses instead of sodium methylate, potassium methylate practically the same yields are obtained ranging in about the following limits:

Yield (per- Phloracetophenone cent of M.P., C.

theory) If various reaction media are used for such trimethylation formulations about the following yields are obtained:

l E is dielectric constant.

As an example of how the products vary with change in the ratio of reactants, a few typical results are given under conditions of methylation similar to the above example where methanol is illustratively used as the solvent.

Yields (percent of theory) for Molar Relationship 3,5-dimethyl, 3,3,5- 3, 5- 3,3.-dimethyl trimethyl tetramethyl Trace 4.0 5.3 25.2 5.4 2.5to 6.0 40 to 10to 10.0 Trace 30.8 35.8

EXAMPLE 2 Isoamyl substituted phloracetophenones To a solution of 4.0 g. phloracetophenone and 1.64 g.

sodium (3 equiv.) in 20 cc. absolute methanol is added under cooling 23 g. isoamyliodide (6 moles). After 5 days standing at room temperature, the clear red solution shows a pH of about 9. This is acidified with 6 cc. 2 N-hydrochloric acid and methanol and the excess isoamyliodide is evaporated (finally in vacuo). The remaining oil is dissolved in 50 cc. methanol to which is added 100cc. petroleum ether warm (B.P. 40-60") and this is diluted with 50 cc. 2% sulfuric acid. .Rapid extraction .is performed and the petroleum ether layerseparates whereby the above compound crystallizes out already to a great extent. The aqueous methanolic layer is extractedtwice witheach 100 cc. .of warm petroleum ether. The combined petroleum ether extracts isolate upon standing 2.96 g. -1 acetyl-3,3; Ttri-isoamylcyclohexa- 1-5-diene-2,6-diol-4-one (33 percent of theory) as-.colorless fine prisms with M.P.. 154-157"; after recrystallization from 80 percent methanol, 'M.P. 161-162". 1 The aqueous methanolic layer-is .diluted with water and chilled, whereupon after several hours crude 3-isoamyl phloracetophenonecrystallizes (0.32 g 5.7percent of theory). After recrystallization from methanol or benzol, slightly yellowprisms M.P. 188 C. are obtained.

EXAMPLE 3 'y,-'y-dimethyl. allyl substituted phloracetophenones To the suspension of 7.0 gphloracetophenone and 2.87 g. of sodium (3 equiv.), dissolved in 40 cc.,methanol, 18.6 g. qw-dimethylallylbromide (3 equiv.) are added during 30 min. under shaking and cooling in brine. After 12 hours standing in the refrigerator and for the same time at room temperature, without filtering from the separated sodium bromide, it is extracted directly with petroleum ether. Themain portionof 3,3,5, ,'y-dimethyl allyl phloracetophenone precipates on chilling the petroleum ether extract. Additional yield is obtained by concentrating the mother liquor. The combined crudes are recrystallized from dilute methanol yielding 5.58 g. (40.5 percent of theory) with-a M.P. of 121 C. From the aqueous methanolic layer, after diluting with water crude- 3-('y,' -di-methylallylphloracetophenone) is obtained 0.46 g. (4.7 percent of theory) M.P. 170-17 1. Recrystallization from dilute methanol resultsin clusters of prisms with M.P. 172C.

EXAMPLE-4 wy-Dimethyl allyl substituted phlorpropiophenone 4.0 g. phlor-propiophenone, 1.52 g. sodium (3 equiv.) in 20 cc. of methanol and 9.82 g. 'y,'y-di-methylallybromide (3 mole) were exchanged with one another as in Example 3 and worked up. After boiling down the petroleum ether extracts (160 ml.) 7.66 g. of resin remain, which produces, after recrystallization from 50 ml. hexane (B.P. 6069 C.) 3.06 g. colorless prisms (36.2 percent of theory) of l-propionyl 3,3,5-tri-'y,'y-dimethylallyl-cyclohexa-l,5-diene-2,6-diol-4-one with M.P. 99 101 C. From the aqueous methanolic layer is obtained 0.27 g. (4.9 percent of theory) 3-'y,'y-dimethyl allyl phlorpropiophenone as colorless prisms (recrystallized from dilute methanol) with M.P. 160-161.

EXAMPLE 5 I-acetyl, 3,3,5, tribenzyl-cyclohexa-J,S-diene- 2,6-di0l-4-0ne 10.0 g. phloracetophenone, 4.10 g. sodium (3 equiv.) dissolved in 50 cc. methanol, are treated during half an hour under strong cooling and stirring with a mixture of 22.6 g. benzylchloride (3 moles) and 25 cc. methanol. After three days of standing in the refrigerator, the clear red solution standing above the sodium chloride precipitate shows a pH of about 8. Acidification is done with 100 cc. 2 percent sulfuric acid and several extractions are made with altogether 250 cc. benzol. Subsequently, the combined benzol extracts are filtered and extracted with successive 30 cc. portions of 50 percent aqueous methanol which have been saturated with potassium bicarbonate. The combined aqueous methanolic potassium bicarbonate extracts are washed with 22 cc. of benzol and then acidified with hydrochloric acid. The oil separating hereby solidifies upon some standing in the refrigerator I (4 equivalents).

e and is suckedofl? the .next day, washed vwithwater to substantial neutrality and .dried: 17.0 g. (65 percent of theory) with M.P. 115; after recrystallization from benzol petroleum ether fine needles combined into bundles with M.P. 118-119" are obtained.

EXAMPLE 6 .1-ucetyl:3+methyl 3,5diethyl-cyclohexa-1,5-a'iene-2,6

To -a solution of 4.0 g.. 3-.methyl, phloracetophenone and 2.37 g..sodium (2.-equ'ivalents) in.20.cc. of absolute methanol, .is. added, .under cooling 13.7 .g. ethyl :iodide After ifive days standing at room temperature, the clear redsolution is acidified with 2 N hydrochloricacid.topHofabout 5;56.0, and the excess ethyl iodide .is evaporated in'vacuo. The remaining oil is dissolved-in 501cc. methanol to which is added :100- cc. warm .petroleum 1ether (.B.P. 40-60") and this is diluted with 50 cc. 2'percent.-sulfuric acid. Rapidextraction is performed, usingztwoadditional100cc. portionsof warm petroleum .ether. fllacetyl *3-methyl-3,S-diethyl-cyclohexa-1,5-diene=2,6-diolg4one crystallizes out of the combined; extracts. on standing, and may .be recrystallized from80 percent:'rnethanol-: yield 30 .percentof theory.

By similar methods, .compounds in :the following table have been made, columns refer to the various 'substituents in:the structural diagramsf R4 Q0 R1 0 R1 HO OH OH Approx. C0R Substituent Locations M.P.,- O. Yield,

' Percent lsovaleryl dlmethylallyl R; I 138. 5-140 9 D0"; 0 R2, R3, R4 93 33. 0 R2 163 3. 5 D R2, R3, R4 109 44. 1 Do R2, R3, R4 143 42. 5 D0 Ra, Ra, R4 100 30. 5 Chlorphen- Hz 197 10. 5

acetyl. Benzoyl R2, R3, R4 152 39 Butyryl 2, R3, R4 106-107 31. 2 isobutyryl. R3, R 91-92 27. 3 2, R3, R4 39-90 29. 2 d0 2, a, 4 89-91 28.0 methyl R2, R3, R4, R 54 35. 8

alkali metal salts of phloracylophenones with a halide selected from the group consisting of primary and secondary alkyl, alkenyl and aralkyl halides having less than twenty carbon atoms in a liquid having a dielectric constant between 10 and 88, such liquid being selected from the group which consists of lower alkanols, lower ketones, water and mixtures thereof. 7

2. The process recited in claim 1 in which the halide compound is the iodide.

3. The process for the production of stable nucleus poly-substituted phloracylophenones, 'which comprises reacting phloracylophenones in the form of alkali metal salts with an alkyl halide having less than twenty carbon atoms, in a liquid having a dielectric constant between 7 10 and 88, said liquid being selected from the group consisting of lower alkanols, lower ketones, water and mixtures thereof.

4. Process for production of nucleus-substituted phloracylophenones which comprises dissolving a phloracylophenone in a lower alkanol having less than five carbon atoms, adding to the solution alkali metal and halide selected from the group consisting of primary and secondary alkyl, alkenyl and aralkyl halides having less than twenty carbon atoms, distilling oil in vacuo the excess alkanol and halide, and thereupon subjecting the residue to fractional extraction and crystallization.

5. Process of producing nucleus-substituted phloracylophenones which comprises treating phloracylophenones in a liquid having a dielectric constant between 10 and 88, said liquid being selected from the group consisting of lower alkanols, lower ketones, water and mixtures thereof, in the presence of alkali metal alcoholate in proportions of alkali metal sufiicient to form alkali metal salt equivalent to the number of moles (from 1 to 4) with which the nucleus is to be substituted, with a halide selected from the group consisting of primary and secondary alkyl, alkenyl and aralkyl halides, having less than twenty carbon atoms, the halide being present in at least stoichiometric proportions to the alkali metal alcoholate added.

6. The process recited in claim 5 as applied to the production of the phenone with a predominance of mono substitution product of the nucleus, by selecting the ratio of phloracylophenone to alkali metal alcoholate to halogen compounds in the range between 1:121 and 1:1:3.

7. The process recited in claim 5, in which the stoichiometric ratio of the alkali metal alcoholate to phloracylophenone is 4:1 and the halide compound is present in excess of 4 equivalents in relation to the phloracylophenone.

8. Process of producing nucleus-substituted phloracylophenones which comprises treating the phloracylophenone in a solvent having a dielectric constant between and of lower alkanols, lower ketones, water and mixtures thereof, in the presence of alkali metal alcoholate in proportion of alkali metal sufiicient to form alkali metal salts at all points in the nucleus where substitution is desired, with a halide selected from the group consisting of primary and secondary alkyl, alkenyl and aralkyl halides having less than twenty carbon atoms, and in which the proportion of the halide in respect to the alkali metal is in the ratio 2:1 to 4:1.

9. The process of producing relatively high yield of tri-nucleus-substituted phloracylophenone by treating the same in a liquid having a dielectric constant between 10 and 88, said liquid being selected from the group which consists of lower alkanols, lower ketones, water and mixtures thereof, in the presence of alkali metal alcoholate with ,'y-dimethyl-allyl halide in which the proportions of the phloracylophenone to alkali metal to halide are between 1:2:4 and 1:4:8.

10. The process for the production of iso-amyl substituted phloracylophenone, which comprises dissolving phloracylophenone in a lower alcohol, and adding 3 molar equivalents of alkali metal alcoholate and three to six molar equivalents of iso-amyl halide, and recovering the reaction products therefrom by fractional extraction and crystallization.

11. l-acetyl, 3,3,5,5-tetra alkyl, cyclohexa-l-ene-Z-ol- 4,6,dione in which the alkyl is a lower alkyl.

References Cited in the file of this patent UNITED STATES PATENTS 

1. PROCESS FOR THE PRODUCTION OF NUCLEUS SUBSTITUTED PHLORACYLOPHENONES WHICH COMPRISES EXCHANGE OF THE ALKALI METAL SALTS OF PHLORACYLOPHENONES WITH A HALIDE SELECTED FROM THE GROUP CONSISTING OF PRIMARY AND SECONDARY ALKYL, ALKENYL AND ARALKYL HALIDES HAVING LESS THAN TWENTY CARBON ATOMS IN A LIQUID HAVING A DIELECTRIC CONSTANT BETWEEN 10 AND 88, SUCH LIQUID BEING SELECTED FROM THE GROUP WHICH CONSISTS OF LOWER ALKANOLS, LOWER KETONES, WATER AND MIXTURES THEREOF.
 11. 1-ACETYL, 3,3,5,5-TETRA ALKYL, CYCLOHEXA-1-ENE-2-OL4,6,DIONE IN WHICH THE ALKYL IS A LOWER ALKYL. 